This invention relates to a caster adjustment arrangement for a hydraulically driven tractor of the type which is supported on a pair of hydraulically driven wheels and a pair of caster wheels and steered by a differential speed between the driven wheels.
Self-propelled windrowers require precise and quick control for field operation at low speeds. Maneuverability is enhanced through the use of a zero caster angle, that is, the pivot axis for the caster wheels is vertical with respect to the machine. A zero caster angle reduces the torque differential required from the drive wheels to steer the tractor by reducing the tendency of the caster wheels to self-steer to a neutral position (self-center). When transporting at higher speeds, quick directional control and lack of self-centering can result unstable directional operation, especially for novice users. Unstable operation can lead to accidents and/or the inability of an inexperienced user the reach full transport speed of the unit.
It would be advantageous to have an adjustment means for altering the caster angle of the caster wheels to an optimal angular position that balances operational maneuverability and transport stability. Further advantages would be realized by a caster angle adjustment that can be easily incorporated into current windrower tractor designs or even retrofit onto existing machines. Still further advantages would be realized by an adjustment means for altering the caster angle of the caster wheels of a windrower tractor that is adaptable for manual, powered, or automatic adjustment.